Shielded electrical coil assembly



g- 1963 H. M. PENNINGROTH 3,

SHIELDED ELECTRICAL con. ASSEMBLY Filed Dec; 1, 1958 INVENTORQ .9 6/.Amy

. FIGURE 3.

SHIELDED ELECTRHCAL (H, ASSEMBLY Herbert M. Penningroth,Halcs Corners,Wis, assignor to General Motors Corporation, Detroit, Mich, a corpmration or Delaware v Filed Dec. 1,1958, Ser. No. 777,423

4 Elaims. (Cl. 836-87) This invention relates to an improved assemblyfor elec trical coils and more particularly to an intermediate frequencytransformer assembly of the type usedin radio for the electricalcomponents is slid-ably fitted within the can and supports terminal pinswhich extend through the chassis for external circuit connection andalso supports a coil form which carries at its upper end a shield coverfor the can. The base is secured to a chassis for wired circuits by ascrew or to a chassis for printed circuits by soldering the terminalpins to the printed circuit conductors. This construction permits thecan to be formed of tube stock, of either rectangular or circular crosssection, and obviates the need for deep-drawn shield can parts. Itgreatly facilitates servicing of the components since removal isaccomplished through the upper end of the can and adjustment of a corewithin the coil form may be made from either side of the chassis.

A more complete understanding of this inven'on may be had from thedetailed description which follows taken with the accompanying drawingsin which: I

FIGURE 1 is a sectional view of the inventive coil assembly on a wiredcircuit chassis taken on lines 1'1 of FIGURE 2;

FIGURE 1; a

FIGURE 3 is a fragmentary view of the coil assembly on a printed circuitchassis with a section taken on lines 33 of FIGURE 4-; and v FIGURE 4 isa bottom View of'the assembly shown in Referring now to the drawings,there is shown an illustrative embodiment of the invention in anassembly for intermediate frequency transformers. As shown inFIG- URES land 2, the IF transformer is installed on a metal chassis plate 10adapted for wire connected circuits and comprises a tubular metal shieldcan 12 which is open at both ends and provided at its lower end with apair of bendable tabs 14 and 16. The tabs extend through an opening orcutout 17 in the chassis and are bent over and soldered thereto toprovide rigid mechanical support and electrical contact. Disposed withinthe can is a base 18 of insulating material which is slidably fittedwithin the can and seated against the portions of the chassis whichextend within the confines of the can 12. The base 13 supports terminalpins 20, 22, and 23. A tubular coil form 24- of insulating material andopen atboth ends has its lower end secured to the base 18 and'extendinginto respective terminal pins. A fixed condenser'32 is disposed FIGURE 2is a bottom View of the assembly shown in cludes'a peripheral flangeembracing ormating with the upper end of the can. The cover completesthe shielding of the components and provides rigid support for thecoilform. The inductance of the coil 30 may be varied for tuning theintermediate frequency transformer by a thread core fidhaving a toolengaging recess in both ends for axial adjustment from either the top orbottom of the chassis. The base 18 is removably secured to the chassisby a screw 36 extending through a clearance hole in the chassis tab 38into threaded engagement with the base 18. With the IF transformerinstalled on a metal chassis for wired circuits, the shield can 12 isfixedly mounted on and electrically connected to the chassis by the tabs14 and 16 and need not be removed for replacement of or servicing theelectrical components contained therein. After disconnecting theexternal wired circuits from the terminal pins and removing the screw36, the base together with the electrical components may be removed fromthe shield can by lifting the shield cover 26. r s

As shown in FIGURES 3 and 4, the same IF transformer is installed on aprinted circuit chassis plate or board 46 of insulating material. Theboard includes commen or ground conductor strips 42 and 44 and circuitconductor strips 46, 43, and 5t} embedded in and adhered to the lowersurface. The shield can 12 is secured to the plate 4%} by the tabs 14and 16 which extend through openings in the board and are bent over andsoldered to the ground conductor strips 42 and 44-. The base 18 is se-'cured to the board by the terminal pins 20, 22, 'and 23 which extendthrough the board 40 in alignment with the circuit conductor strips 46,48, and 50 and are soldered thereto. The board defines an access passage52 in align ment with the coil form. I

When the IF transformer is used on the printed circuit board, the shieldcan 12 may remain fixedly mounted on the board and the base 18 togetherwith the electrical components may be removed from the top of thechassis, after unsoldering the terminal pins, by lifting the shieldcover 26. The thread core is accessible fromeither open end of the coilform for adjustment of the IF transformer frequency.

Although the description of this invention has been given with respectto a particular embodiment, it is not adjacent the coil form" andsupported by its lead wires to be construed in a limiting sense.Numerous variations and modifications within the spirit and scope of theinvention will now occur to those skilled in'the art. For a [definitionof the invention, reference is made to the appended claims.

I claim:

1. In combination with an electrical chassis having two sides definingan opening and being adapted to support electrical conductors on oneside thereof; a tubular shield can disposed on the other side of thechassis over said opening and being open at'both ends, the lower end ofthe can including a pair of oppositely disposed integral tabs extendingthrough the chassis and bent over to per- "lower end of the can andformed ofinsul-ating material defining a central opening, a plurality ofterminal pins supported by and extending through the base, a tubularcoil form open at both ends, a core movably mounted within the coilform, the coil form having a lower end extending intothe'central openingand secured to the base whereby the core is accessible through thecentral opening in the base, a coildisposed on the coil form andelectrically connected with the terminal pins, and a shield coverincluding a peripheral flange surrounding the upper end of the can anddefining a central opening surrounded by an annular flange, the upperend of the coil form mating with and secured to the annular flangewhereby the core'is accessible through the central opening in the coverand the peripheral flange of the cover forms a grasping portion forremoval of the coil assembly from the can, and fastening meansoperatively connected with the base for securing it to the chassis.

2. In combination with an electrical chassis having two sides anddefining an opening and being adapted to support electrical conductorson one side thereof, a tubular shield can disposed on the other side ofthe chassis over said opening and being open at both ends, means. at thelower end of the can for securing it to a chassis, a removable coilassembly comprising a support base disposed Within the lower end of thecan and formed of insulating material tdefining a central opening, aplurality of terminal pins supported by and extending through the base,a tubular coil form open at both ends, a core movably mounted within thecoil form, the coil formhaving a lower end extending into the centralopening and supported by the base whereby the core 'is accessiblethrough the central opening in the base, a cover including a peripheralflange and a central opening surrounded by an annular flange, saidannular flange being disposed over andsecured to the upper end of thecoil form whereby the core is'accessible through the central opening inthe cover, a coil on said coil torm having a pair of terminalselectr-ically connected respectively with a pair of the terminal pins, ascrew adapted to extend through the chassis into threaded engagementwith said base for securing the base against the chassis with theperipheral flange of the cover surrounding the upper end of the shieldcan, said core having a tool engaging recess on both ends for adjustmentfrom either side of the chassis.

3. In combination, a removable coil assembly comprising a tubular shieldcan open at both ends, a shield cover including a peripheral flangesurrounding the upper end of the can and defining a central openingsurrounded by an annular flange, the lower end of the can terminating ina pair of oppositely disposed tabs, a chassis plate of insulatingmaterial having two sides and defining an opening and including a pairof conductive strips adhered to one side thereof, the lower end of thecan being disposed on the other side of the plate with the tabsextending through the plate and bent over to permanently secure thetabswith respective strips, a support base of insulating materialdisposed within the can adjacent the plate and defining a centralopening, a plurality of terminal pins extending through and supported bythe base, a tubular coil form open at both ends, a core movably mountedwithin the coil form, the coil form having a lower end extending intothe central opening in the base and secured to the base whereby the coreis accessible through the central opening in the base, a coil disposedon the form and electrically connected with the terminal pins the upperend of the coil form mating with and secured to the annular flangewhereby the core is accessible through the central opening in thecoverand the peripheral flange of the cover forms a grasping portion forremoval of the coil assembly from the can, said plate including pluralcircuit strips adhered to one side thereof and aligned with respectiveterminal pins, said pins extending through the respective circuit stripsand being soldered thereto.

4. In combination, a removable coil assembly comprising a tubular shieldcan open at both ends, the lower end of the can including a pair ofoppositely disposed integral tabs, a chassis plate of insulatingmaterial having two sides and defining a pair of openings alignedrespectively with said tabs and including a pair of conductive stripsadhered to one side adjacent the openings, the lower end of the canbeing disposed on the other side of the plate with said tabs extendingthrough the openings and being bent-over into permanent contact with theconductive strips, a support base formed of insulating material disposedwithin the shield can adjacent the plate and defining a centralaperture, a plurality of terminal'pins supported by and extendingthrough the base, a tubular coil form open at both ends, having thelower end disposed in the aperture and supported by the base, a coilsupported on the coil form and connected electrically to the terminalpins, a shield cover including a peripheral flange and defining acentral passage surrounded by an annular flange, the upper end of thecoil form mating Withv and secured to the annular flange, said plateincluding a plurality of conductive circuit strips adhered to said oneside, the plate and circuit strips defining apertures aligned withrespective terminal pins which pass therethroughand are soldered to therespective circuit strips with the peripheral flange of the coverembracing the upper end of the shield can, said plate also defining apassage in alignment with the coil form, and a thread core movablymounted in the coil formaccessible from either end thereof.

References titted in the file of this patent UNITED STATES PATENTS

1. IN COMBINATION WITH AN ELECTRICAL CHASSIS HAVING TWO SIDES DEFINING AN OPENING AND BEING ADAPTED TO SUPPORT ELECTRICAL CONDUCTORS ON ONE SIDE THEREOF; A TUBULAR SHIELD CAN DISPOSED ON THE OTHER SIDE OF THE CHASSIS OVER SAID OPENING AND BEING OPEN AT BOTH ENDS, THE LOWER END OF THE CAM INCLUDING A PAIR OF OPPOSITELY DISPOSED INTEGRAL TABS EXTENDING THROUGH THE CHASSIS AND BENT OVER TO PERMANENTLY SECURE THE CAN TO THE CHASSIS, A REMOVABLE COIL ASSEMBLY COMPRISING A SUPPORT BASE DISPOSED WITHIN THE LOWER END OF THE CAN AND FORMED OF INSULTING MATERIAL DEFINING A CENTRAL OPENING A PLURALITY OF TERMINAL PINS SUPPORTED BY AND EXTENDING THROUGH THE BASE, A TUBULAR COIL FORM OPEN AT BOTH ENDS, A CORE MOVABLY MOUNTED WITHIN THE COIL FORM, THE COIL FORM HAVING A LOWER END EXTENDING INTO THE CENTRAL OPENING AND SECURED TO THE BASE WHEREBY THE CORE IS ACCESSIBLE THROUGH THE CENTRAL OPENING IN THE BASE, A COIL DISPOSED ON THE COIL FORM AND ELECTRICALLY CONNECTED WITH THE TERMINAL PINS, AND A SHIELD COVER INCLUDING A PERIPHERAL FLANGE SURROUNDING THE UPPER END OF THE CAN AND DEFINING A CENTRAL OPENING SURROUNDED BY AN ANNULAR FLANGE, THE UPPER END OF THE COIL FORM MATING WITH AND SECURED TO THE ANNULAR FLANGE WHEREBY THE CORE IS ACCESSIBLE THROUGH THE CENTRAL OPENING IN THE COVER AND THE PERIPHERAL FLANGE OF THE COVER FORMS A GRASPING PORTION FOR REMOVAL OF THE COIL ASSEMBLY FROM THE CAN, AND FASTENING MEANS OPERATIVELY CONNECTED WITH THE BASE FOR SECURING IT TO THE CHASSIS. 